Apparatus for the extraction of sheets

ABSTRACT

Apparatus for the withdrawal of sheets from a stack comprises a unit to receive a major stack of the sheets, a collecting unit in which a minor stack of constant height is formed of sheets withdrawn from the major stack, and means effective to separate and feed forwardly the lowermost sheet in the minor stack.

U ite States atet 1191 Donner Mar. 11, 1975 APPARATUS FOR THE EXTRACTION OF 3,173,684 3/1965 Binzoni et a1 271/122 x 3,191,927 6/1965 Hartbauer et a1 271/D1G. 7 SHEETS 3,339,917 9/1967 Petrovsky 271/122 [75] In entor: SIgmar D er, gs g, G y 3,488,048 1/1970 Dykaar ct a1. 271/122 x 1731 Assigns-9 K191191919 & Maschinenfabrik, 327%??? 13/133? 22312321331111: 111531131813 Augsburg Germany 3,705,719 12/1972 Polit 6t 21!. ,1 271/1310. 7 [22] Wed: 1973 FOREIGN PATENTS OR APPLICATIONS [21] Appl. No.: 324,355 1,141,116 12/1962 Germany ..271/1)1G.7

[30] Foreign Application Priority Data 5 E B H S J ssistant xaminerruce toner, r. Jan. 26, 1972 Germany 2203626 Attorney, g or Firm Karl F. Ross; Herbert 52 us. (:1 271/3.1, 271/35, 271/119, Dubno 271/122, 271/146, 271/162, 271/165 [51] Int. Cl. B65h l/30, B65h 3/04 [57] ABSTRACT [58] held of Search 271/4 Apparatus for the withdrawal of sheets from a stack Til/35 165-167 comprises a unit to receive a major stack of the sheets, a collecting unit in which a minor stack of constant height is formed of sheets withdrawn from the major [56] References cued stack, and means effective to separate and feed for- UNITED STATES PATENTS wardly the lowermost sheet in the minor stack. 2,359,856 10/1944 Morse 271/125 2.737.388 3/1956 Gottscho 271 138 x 8 Clams 9 Drawmg F'gures FATENTED 1 I975 ShiU 1 UP 4 APPARATUS FOR THE EXTRACTION OF SHEETS FIELD OF THE INVENTION The invention relates to apparatus for the extraction or withdrawal of sheets, such as documents, vouchers, records or tabulating cards and checks, in which the lowermost sheet is extracted from a pile or stack and subsequently separated with simultaneous acceleration of the speed of extraction or withdrawal.

BACKGROUND OF THE INVENTION Withdrawal or extraction units by which single sheets withdrawn at the top, the bottomor laterally from a pile or stack of documents or sheets and transferred to a conveying or feeding device are known. An extraction unit, of this type may, operate with a conveyor belt having a high coefficient of friction and a counterrunning feed belt having a low coefficient of friction the effect of which is increased by means of a suction or vacuum shoe.

Wherever single sheets are to be extracted from the bottom of a stack or pile of documents, vouchers or the like, substantial difficulties are encountered, since the effectiveness of such extraction depends directly upon the weight ofthe paper resting on the extraction rollers, tapes or belts. A stack or pile of this kind can thus be filled with only a relatively small quantity of paper, since otherwise satisfactory operation cannot be ensured. The stack or pile of documents or sheets has to be replenished at short intervals of time with the result that the operation of the machine is severely impeded. The temporary increase in weight resulting from replenishment of a small pile, is so substantial as to involve the risk of two sheets being withdrawn simultaneously or the risk of a non-observance of the gap between the documents during their conveyance.

In the art of printing, the withdrawal of two or more sheets simultaneously is generally not considered a disadvantage, since it is taken for granted that a concealed sheet cannot be printed and thus at most constitutes waste. However, the occurrence of a fault of this kind in data processing or like operation may result in incomplete or even incorrect information or readings which must be avoided.

OBJECTS OF THE INVENTION It is an object of the invention to provide an improved extraction unit for sheets of any kind which fully ensures that only single sheets are extracted from a stack or pile of any height.

It is a further object of the invention to provide such an extraction unit of substantially simplified construction and which provides improved guidance of the sheets and automatic control.

SUMMARY OF THE INVENTION In accordance with the invention, a collecting unit for forming a partial or minor sheet stack or pile of an adjustable, constant height is inserted between a processing unit and a stack or pile containing a larger quantity of the sheets, the lowermost sheet being fed from the partial, minor or small stack or pile to the processing unit.

It has been found to be particularly advantageous for the collecting unit to comprise a fixed stop contacted by the leading edges of the sheets extracted from a stack and aligning these edges, means for limiting the height of the intermediate or minor stack or pile, and a withdrawal unit acting upon the lowermost sheet, the planes of conveyance of the withdrawal unit associated with the major stack or pile and of the withdrawal unit of the collecting unit advantageously forming an acute angle with opposed directions of feed of the withdrawal units respectively associated with the major stack or pile and with the collecting unit.

The construction according to the invention affords the advantage that it is unnecessary to ensure that actually only one or more sheets are extracted from a stack or pile-This advantage results from the fact that the sheets withdrawn are fed initially to the collecting unit which operates in a manner similar to a balance to ensure that only a partial or minor stack or pile of a determined height and determined weight can form therein. It is thus ensured that sheets at the bottom of the partial or minor stack or pile are extracted therefrom singly and subsequently separated. The major stack or pile may thus be replenished with any number of sheets at longer time intervals. i

In. one modified embodiment of the invention, the major stack or pile unit is provided above the processing unit and is of a tiltable construction and may be locked in the desired tilted position. This afford the advantage that the stack or pile unit may be swung clear to allow free access to the separating unit for carrying out assembly operations or fitting or for clearing a defeet.

The axis of rotation or pivoting of the major stack unit is advantageously provided in the zone of the axis of the leading roller or cylinder of the extraction unit associated with that stack thus facilitating positioning at the most advantageous angle at which the documents withdrawn from the stack may be fed to the collecting unit.

A further advantageous embodiment of the invention may be obtained by constructing the limiter used for producing a partial or minor stack or pile (in the collecting unit) of a determined maximum height in such manner as to enable it to serve as a control element by which the withdrawal or extraction unit associated with the major stack or pile is controlled in such a manner as to stop operation of that withdrawal or extraction unit when the height of the partial or minor stack or pile reaches a determined maximum value.

The limiter advantageously comprises at least one strap connected to a micro-switch below which strap the partial or minor stack or pile is formed, a break pulse being generated when the strap is lifted or pushed aside. A reliable control of the formation of a partial or minor stack or pile of a constant height is thus ensured.

In the withdrawal of sheets which have previously been repeatedly used, it cannot be avoided that the edges of the sheets are deformed to a certain extent by tears, creases, waviness or the like. In accordance with the invention, these sheets, too, are withdrawn singly, since the front wall of the unit of the major stack or pile and/or the front wall of the collecting unit consists of a plate which is bevelled at the bottom, the bevel facing the major stack or the partial or minor stack being covered at least at one position by a smaller, vertically adjustable, plate or lamella limiting the height of the gap forming the outlet. The gap'forming the outlet is thus limited solely by the bottom edge of the lamella and any deformation of sheets occurring laterally thereof is thus prevented from having a negative effect and may be easily smoothed out by the bevel of the plate during the withdrawal operation.

In one embodiment of the invention, the extraction unit associated with the collecting unit is provided with a least one device, for example one or more noncircular rollers or the like, by which jolts or vibrations acting upwardly upon the minor stack or pile may be generated. This construction affords the advantage that the minor stack or pile is loosened to facilitate removal of the lowermost sheet therefrom.

In accordance with the invention, the disadvantage of two or more sheets being on the point of leaving the collecting unit is avoided by providing the separating unit with at least two feed elements, such as rollers, acting upon the incoming sheet at different peripheral speeds, and at least one retarding device, such as a roller, a rotating belt, tape or the like acting downwardly upon the incoming sheet in the opposite direction to the direction of feed thereof. Moreover, at least one hold-down device, for example a curved plate, may advantageously be provided downstream of the outlet of the collecting unit, the hold-down device being effective to press the sheet issuing from the collecting unit against the feed element.

One of the feed elements and the retarding device are advantageously provided in a manner similar to a pair of feed or drawing rollers but rotating in the same direction and carrying discs which do not contact each other and the radial spacing of which may also be adjustable.

These means are effective on the one hand to bring the sheet to be extracted or drawn-off into adequate frictional contact with the conveyors and, on the other hand, to ensure that any accidentally conveyed sheet above the sheet to be withdrawn is reliably held back. Those feed elements of the separating unit that rotate at the highest speed thus engage only which particular sheet that is actually to be withdrawn, the sheet being then passed at a correct distance from the preceding sheet to further processing stations.

DESCRIPTION OF THE DRAWING The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which:

FIG. 1 is a diagrammatic side elevation of the extraction unit with documents therein;

FIG. 2 is a corresponding plan view along the line C-C of FIG 1;

FIG. 3 is a plan view along the line BB of FIG. I;

FiG. 4 is a front elevation of detail A in FIG. 1;

FIG. 5 is a side elevation of a further embodiment;

FIG. 6 is a plan view along the line D-D of FIG. 5;

FIG. 7 is a front elevation of a separating unit in which the rollers are provided in laterally staggered relation',

FIG. 8 is a side elevation of the construction shown in FIG. 7; and

FiG. 9 is a front elevationofa separating unit with superimposed rollers.

DESCRIPTION OF THE DRAWING The main units shown in the drawings include a major stack or pile unit 29, a collecting unit and a separating unit 31.

Main Stack Unit 29 The main-stack unit 29 is diagrammatically illustrated in FIGS. 1, 3 and 4. Two conveyor belts 11 run about rollers 8 and 10. One of the rollers 8 or 10 is driven through an electromagnetic clutch (not shown) which is switched on and off by a microswitch 19 provided in the collecting unit 30. The rollers or cylinders 9, which are not directly driven, serve merely to support the conveyor belts 11. A plate 15 is provided with a bevel at the bottom and with one or more rectangular, small plates or lamellae 16 in the middle or at laterally displaced positions.

FIG. 1 shows a large stack or pile of documents or sheets 21 inserted in the unit 29. When the conveyor belts 11 are switched on and thus start to move, small piles of documents, that is to say, several superimposed documents or several documents overlapping in the manner of fish scales are conveyed through the slot forming the outlet between the plate 15 and the roller 8 or the conveyor belt 11, into the collecting unit 30.

As mentioned previously, the bevel'of the plate 15 and the rectangular lamellae 16 perform an important function, the bevel ensuring reliable conveyance of documents having imperfect edges, and the lamellae or lamellae 16 limiting the number of sheets.

The same principle and the same construction are employed in the collecting unit 30 in which there is provided a bevelled plate 13 having a lamellae 14.

FIG. 4 shows a front elevation of a detail of the plates 15 or 13 and of the lamellae 16 or 14.

The whole unit 29 is swingable about the central axis of the roller 8 at pivot 8. The pivot bearings are provided with a frictional device enabling the receptacle or unit to remain in any optional position. Alternatively, a plurality of fixed locking positions may be provided. eg as diagramatically shown at 29a. The unit 29 is adjustable for the following two important reasons: When the separating unit 31 disposed exactly below the unit 29 is clogged or obstructed by paper, or for any other reason, the whole unit 29 may be swung upwards thus affording better access to the parts below it, namely the separating unit 31 or the conveying device. In normal operation, the unit 29 is tilted at the angle substantially determined by the length of the respective documents in such manner that the documents transferred from the unit 29 to the collecting unit 30 run substantially into the gap a of the strap 18 provided on the microswitch 19. The adjustment is not very critical, since the documents are allowed to contact the bottom of the collecting unit 30 before contacting the stop 17.

Collecting Unit 30 The collecting unit 30, which is diagrammatically illustrated in FIGS. 1 and 2 comprises, among other component parts, the rollers 3, 4 and 5 to which the documents from the stack 29 are fed. The documents contact a stop 17 which may be adjusted to the length of the respective documents. A microswitch 19 is secured at a position below the rear stop 17, preferably to the underside of the stop 17. The switch lever of the microswitch 19 is extended into a wire strap 18. It will be understood that the strap 18 may be made of a variety of metals or of a synthetic resin. The wire strap is so contructed as to project laterally from the stop 17 at an adjustable distance a from the lower, documentsupporting surface. In the illustrated inoperative position, the contact of the microswitch 19 is closed; when the withdrawal operation is switched on, the belts 11 are driven through an electromagnetic clutch (not shown). The documents 21 are thus introduced into the collecting unit 30 at a position below the strap 18 until the minor stack in the collecting unit 30 has attained the height a. The strap 18 is then forced to move clear by subsequent documents 21, thus operating the microswitch 19 whereby the supply of documents is stopped. When the height of the minor stack is below the level a, the microswitch 19 is automatically operated whereby the supply of documents to the collecting unit 30 is re-started. The height a of the stack in the collecting unit 30 is adjustable in order to ensure that a substantially constant weight is applied by the paper to the rollers 3, 4 and 5.

The documents 21 are fed by the driven rollers 3, 4 and 5 to a separating unit 31. The roller 5 is constructed as a vibrating roller which is flat on two sides. The vibrating orjarring process has a positive influence upon the separating operation in the separating unit 31 and particularly improves the separation of individual documents 21. Either a single vibrating roller 5, as shown in the drawings, or a pair of rollers similar to the pairs of rollers 3 and 4 may be provided. The rollers are conventionally made of or covered with a material, for example rubber, Vulkolan or the like, which has good paper-gripping properties. The documents 21 leave the collecting unit 30 through a device comprising a plate 13 provided wth a bevel and a lamellae 14 of the kind described in relation to the main stack unit 29.

Separating Unit 31 The separating unit 31 comprises essentially rollers 1 and 2 and a hold-down sheet or member 12. The separating unit 31 is diagrammatically illustrated in FIGS. 1, 2, 5, 6, 7, 8 and 9. The rollers 1, which move in the direction of conveyance or feed, constitute the actual extraction or withdrawal rollers. Their peripheral speed corresponds to the peripheral speeds of the rollers 3 and 4. The peripheral speed of the rollers 1, 3 and 4 is, however, below the peripheral speed of the rollers 6 and 7 on the path of conveyance downstream of the rollers l and 2. The speed at which a document 21 reaching the rollers 6 and 7 is extracted from the separating unit exceeds the speed at which the next docu ment 21 can be brought up with the result that a gap or interval is formed between the documents 21 which are fed forward by the separating unit 31. The rollers 1 may be mounted on a cylinder as shown in FIGS. 7, 8 and 9. The rollers 1 are fixed and thus not adjustable. The rollers 2, which are disposed above the rollers 1, rotate in the opposite direction at considerably lower peripheral speeds, for example only half the speed of the rollers 1. The roller 2 performs the following function:

Since only exactly one document 21 is to be withdrawn, all subsequent documents are held back by the rollers 2. When a document disposed below (between) the rollers 1 and 2 in the extraction unit is followed by a second document or by several documents 21, such subsequent documents are either held back by the rollers 2 or are returned thereby to the feed compartment 30 since they move in the opposite direction to the direction of withdrawal. Where paper of different thicknesses is involved, a satisfactory operation of the retaining or retarding rollers 2 may be ensured by providing them of a vertically adjustable construction so that the gap between the rollers 1 and 2 may be adjusted to substantially the thickness of the paper. A hold-down plate 12 presses the document 21 disposed above the drawing-off or extraction rollers 1 against the rollers 1 under a light pressure and lifts it off the rollers 2 thus ensuring that the force applied to the document 21 in the direction of conveyance exceeds the force applied thereto in the opposite direction. The document may leave the separating unit 31 without stopping. The holdvdown plate or plates 12 thus have to become operative whenever the feed compartment 30 contains one or more documents 21. When the collecting unit 30 contains a normal stack of documents 21 the height of which corresponds to an adjusted value, the documents 21, as a result of their weight, perform substantially the function of the holding-down plate or plates 12.

FIG. 7, 8 and 9 show two alternative constructions of separation unit 31. In FIG. 7, counter-rotating rollers 2 are disposed in the gaps between the rollers 1, the rollers 2 being, moreover, slightly narrower than the rollers l. The hold-down plates 12 are provided to the right and to the left of the outer rollers 1. This is a more advantageous construction than the construction illustrated in FIG. 9, inasmuch as the adjustment of the rollers 2 to the thickness of the paper is less critical than in the construction shown in FIG. 9.

In the embodiment illustrated in FIG. 9, the counterrotating rollers 2 are disposed at positions exactly above the rollers l. The hold-down plate 12, which is constructed as a single plate, engages, in addition, between the rollers 1 and 2. The plate is provided with recesses at positions above and below the rollers. The hold-down plates 12 ensure also that the upper surface of the document 21 between the rollers l and 2 is contacted not at all or only slightly by the counterrotating rollers and the typed or written matter on the document 21 is prevented from being blurred or erased.

FIGS. 5 and 6 show a further construction of the collecting unit 30 and of the separating unit 31. The rollers l, 3 and 4 are replaced by rollers 22, 25 and 26 which drive one or more belts 27 by which the documents 21 are fed to the separating unit 31 and thence to the path of conveyance.

The counterrotating rollers 2 are replaced by contrarotating rollers 23 and 24 and a belt 28. As viewed from the collecting unit 30, a V-shaped gap is formed between the belts 27 and 28. The roller 23 is also adjustable in the upward or downward direction.

As indicated in FIG. 6, the counterrotating belt 28 may be provided between the belts 27. However, a plurality of belts 28 may be provided exactly above the belts 27. Belts of this design are particularly capable of ensuring that the documents 21 are held more reliably in position laterally during the extraction and separating operations and also ofensuring a reduced displacement or canting of the documents issuing from the extraction unit.

It is to be understood that the terms sheet" and sheets whenever used in the following claims include record and tabulating sheets and cards, back checks and other documents which may be subject to data processing or similar operation.

I claim:

1. An apparatus for feeding sheets to a processing unit, comprising:

a magazine adapted to receive a main stack of sheets of variable height and having a support surface at the bottom of the magazine and an outlet at said surface for passing sheets from the bottom of said main stack in one direction;

first feed means for advancing sheets from the bottom of said main stack through said outlet in said direction;

a further surface disposed below the first-mentioned surface and ahead of said outlet in said direction for receiving a minor stack of sheets, said first surface being inclined at an acute angle to said further surface;

an abutment extending generally transversely to said further surface remote from said outlet for intercepting leading edges of sheets fed through said outlet and depositing same upon said further surface in said minor stack with the sheets thereof aligned along said edges;

second feed means for drawing the lowermost sheet from said minor stack and advancing same beneath said magazine in the opposite direction with the aforementioned edges of the sheets withdrawn from said minor stack trailing in said opposite direction; and

stack-height-detection means on said abutment and responsive to the height of the minor stack on said further surface for controlling said first means to maintain at least the maximum height of said minor stack constant.

2. The apparatus defined in claim 1, further comprising means for supporting said magazine for pivotal movement about a horizontal axis to adjust said angle; and means selectively locking said magazine in one of its angular positions relative to said further surface.

3. The apparatus defined in claim 2 wherein said first feed means includes a plurality of rollers spaced apart along said first surface, said magazine being pivotal about the axis of the roller proximal to said outlet.

4. The apparatus defined in claim 1 wherein said stack-height-detection means includes a switch operable to deactivate said first feed means upon said minor stack attaining said maximum height.

5. The apparatus defined in claim 1 wherein said outlet is formed by a plate having a beveled bottom edge and at least one lamellae adjustable in a vertical direction and partly overhanging said beveled edge.

6. The apparatus defined in claim 1, further comprising an upright plate spaced from said abutment along said further surface and formed with a beveled edge inclined downwardly in said opposite direction, and at least one vertically adjustable lamellae partly overhanging said beveled edge.

7. The apparatus defined in claim 1 wherein said second feed means includes at least two elements engageable with a sheet on said further surface for advancing same in said opposite direction, and at least one retarding device engageable with a sheet entrained in said opposite direction and acting thereon in said one direction.

8. The apparatus defined in claim 7, further comprising a hold-down device pressing the sheets down from the bottom of said minor stack against one of said elements. 

1. An apparatus for feeding sheets to a processing unit, comprising: a magazine adapted to receive a main stack of sheets of variable height and having a support surface at the bottom of the magazine and an outlet at said surface for passing sheets from the bottom of said main stack in one direction; first feed means for advancing sheets from the bottom of said main stack through said outlet in said direction; a further surface disposed below the first-mentioned surface and ahead of said outlet in said direction for receiving a minor stack of sheets, said first surface being inclined at an acute angle to said further surface; an abutment extending generally transversely to said further surface remote from said outlet for intercepting leading edges of sheets fed through said outlet and depositing same upon said further surface in said minor stack with the sheets thereof aligned along said edges; second feed means for drawing the lowermost sheet from said minor stack and advancing same beneath said magazine in the opposite direction with the aforementioned edges of the sheets withdrawn from said minor stack trailing in said opposite direction; and stack-height-detection means on said abutment and responsive to the height of the minor stack on said further surface for controlling said first means to maintain at least the maximum height of said minor stack constant.
 1. An apparatus for feeding sheets to a processing unit, comprising: a magazine adapted to receive a main stack of sheets of variable height and having a support surface at the bottom of the magazine and an outlet at said surface for passing sheets from the bottom of said main stack in one direction; first feed means for advancing sheets from the bottom of said main stack through said outlet in said direction; a further surface disposed below the first-mentioned surface and ahead of said outlet in said direction for receiving a minor stack of sheets, said first surface being inclined at an acute angle to said further surface; an abutment extending generally transversely to said further surface remote from said outlet for intercepting leading edges of sheets fed through said outlet and depositing same upon said further surface in said minor stack with the sheets thereof aligned along said edges; second feed means for drawing the lowermost sheet from said minor stack and advancing same beneath said magazine in the opposite direction with the aforementioned edges of the sheets withdrawn from said minor stack trailing in said opposite direction; and stack-height-detection means on said abutment and responsive to the height of the minor stack on said further surface for controlling said first means to maintain at least the maximum height of said minor stack constant.
 2. The apparatus defined in claim 1, further comprising means for supporting said magazine for pivotal movement about a horizontal axis to adjust said angle; and means selectively locking said magazine in one of its angular positions relative to said further surface.
 3. The apparatus defined in claim 2 wherein said first feed means includes a plurality of rollers spaced apart along said first surface, said magazine being pivotal about the axis of the roller proximal to said outlet.
 4. The apparatus defined in claim 1 wherein said stack-height-detection means includes a switch operable to deactivate said first feed means upon said minor stack attaining said maximum height.
 5. The apparatus defined in claim 1 wherein said outlet is formed by a plate having a beveled bottom edge and at least one lamellae adjustable in a vertical direction and partly overhanging said beveled edge.
 6. The apparatus defined in claim 1, further comprising an upright plate spaced from said abutment along said further surface and formed with a beveled edge inclined downwardly in said opposite direction, and at least one vertically adjustable lamellae partly overhanging said beveled edge.
 7. The apparatus defined in claim 1 wherein said second feed means includes at least two elements engageable with a sheet on said further surface for advancing same in said opposite direction, and at least one Retarding device engageable with a sheet entrained in said opposite direction and acting thereon in said one direction. 